A commonly known pump includes a chamber provided with two through openings, via which the chamber is communicable with an external environment and a fluid can flow into and out of the chamber. An impeller is a rotary member arranged in the chamber of the pump. When the impeller rotates, it produces a centrifugal force and a change of pressure in the pump chamber. As a result, the fluid is sucked into the chamber via one of the two through openings and then discharged from the chamber via the other through opening. In this manner, the pump can achieve the purpose of pumping and delivering the fluid.
Conventionally, the blades formed on the impeller are respectively in the form of a thin plate. To prevent portions of each blade near two lateral sides of a radially outer end thereof from interfering with an inner wall surface of the pump chamber, the outer end of each blade is designed to have a largely reduced thickness than other portions of the blade and accordingly, has a relatively sharp edge. The radially outer ends of the impeller blades with relatively sharp edges tend to oscillate when they are subjected to a force applied thereto by the fluid flowing through the pump. As a result, a relatively large noise is produced when the pump operates. Further, local thermal stress tends to occur at the oscillated outer ends of the blades to speed up material fatigue at the blade outer ends and shorten the service life of the blades.
It is therefore tried by the inventor to develop an improved impeller blade structure to solve the problems and disadvantages of the prior art impeller for pump.